Imagine the car being full with just 2.64 gallons...and then driving nearly 690 miles. Volkswagen's latest plug-in hybrid can do just that.

2014 Volkswagen XL1: At 261 mpg, the world's most efficient production car

Volkswagen XL1

Imagining stopping at the gas station and filling up with just 2.64 gallons? The XL1 holds just that much, powering its tiny 47-horsepower, two-cylinder diesel engine. The car is also aided by a 27-horsepower electric motor that lets the vehicle run for up to 32 miles as an electric vehicle.